2015 Vol. 32, No. 1
Display Method:
2015, 32(1): 1-23.
doi: 10.11804/NuclPhysRev.32.01.001
Abstract:
This paper reviews the systematic investigations and understanding for the shape transitions and coexistence with regard to triaxial deformations in A s 100 to 126 neutron-rich Rh (Z = 45), Pd (Z = 46), Ag (Z = 47), Cd (Z = 48) and Zr (Z = 40), Nb (Z = 41), Mo (Z = 42), Tc (Z = 43) isotopes with Z beyond and below Ru (Z = 44), respectively, in Ru the maximal triaxial deformation having been predicted and deduced. The recent measurements and studies of prompt triple- and four-fold, γ-γ-γ and γ-γ-γ-γ, coincidence data from the spontaneous fission of 252Cf using Gammasphere have yielded considerable expansion and extension or first observation of the bands in Ru, Pd, Cd, and Nb isotopes,which provided important data for the studies of nuclear shapes in this region. Combined with previous investigations, recent systematic studies of the new data well reproduced by PES, TRS, PSM, CCCSM and SCTAC model calculations have traced shape changes along the isotonic and isotopic chains, respectively,and with changing excitations/spins as well, significantly expanding our knowledge of shape transitions/coexistence in nuclei.For the neutron-rich Ru and beyond, Rh, Pd, Ag and Cd isotopes, triaxial deformations γ= 28°,slightly smaller than the maximal value, were deduced in Rh (Z = 45) isotopes, with chiral symmetry breaking proposed in 103-106Rh; onset of wobbling motions were identified in 112Ru and 114Pd (N =68),and probably also in 114Ru (N =70); evolution from chiral symmetry breaking in 110,112Ru with maximal triaxial deformations to disturbed chirality in 112,114,116Pd with less pronounced triaxial deformations was proposed; rich nuclear structure was proposed in soft Ag isotopes with possible chiral doubling structure suggested in 104,105Ag, and softness towards triaxial deformation proposed in heavier 115,117Ag;quasi-particle couplings, quasi-rotations and soft triaxiality were suggested in Cd (Z =48) isotopes with small deformations; onset of collectivity was recently suggested in 122,124,126Cd in the vicinity of Z =50 and N = 82 closed shells by studies of Coulomb excitations; shape evolutions from maximal triaxial deformations in Ru (γ=30°, with triaxial minimum energy gain of 0.67 MeV), through Rh with large triaxial deformations ( γ=28°), to less pronounced triaxiality in Pd (with triaxial minimum energy gain of 0.32 MeV), then soft triaxiality in Ag, and finally to slightly deformed Cd isotopes but with emergence of collectivity and soft triaxiality were proposed. The systematic studies of the band crossings in Pd revealed up-rising drivings of the first band crossings caused by (νh11/2)2 and down-sloping drivings of the second band crossings by (πg9/2)2, explained the onset of wobbling motions in 114Pd,and showed a long-sought picture of shape evolution and coexistence in the Pd isotopic chain which is more complete but complex than earlier predictions. Based on the systematic studies in the mass region,maximal triaxial deformation is found to be reached in 112Ru and less-pronounced triaxiality centered at 114Pd, both for N =68, four neutrons more than predicted in earlier theoretical calculations.In the neutron-rich Zr (Z =40), Nb (Z =41), Mo (Z =42) and Tc (Z =43) isotopes with Z just below Ru, large quadrupole deformations of axially symmetric shapes were deduced in Y and Zr isotopes, with emergence of the degree of freedom having been suggested for heavier Zr isotopes; medium triaxial deformations were deduced for the ground states of heavier (A > 104) Nb isotopes, and, with increasing excitations and spins, evolution from medium triaxial deformations with strong quadrupole deformations at ground states to nearly axially-symmetric shapes were deduced; light Nb isotopes (A6103) have near axially-symmetric shapes with strong quadrupole deformations; combining with the identification of onset of strong quadrupole deformation at 100Nb in the Nb isotopic chain, an increase of soft triaxiality with increasing neutron number was proposed in 100-106Nb. Shape coexistence with regard to soft triaxiality is also proposed in Nb isotopes; large triaxial deformations, vibrations and chiral doublets were proposed in Mo isotopes; chiral doubling and large triaxial deformations (γ ~26°) slightly smaller than the maximal triaxiality were suggested in Tc isotopes.The neutron-rich nuclei with Z ranging from 41 through 48 and A ~100 to 126, especially the Pd and Nb isotopes are thus found to be transitional nuclei with regard to triaxiality.
This paper reviews the systematic investigations and understanding for the shape transitions and coexistence with regard to triaxial deformations in A s 100 to 126 neutron-rich Rh (Z = 45), Pd (Z = 46), Ag (Z = 47), Cd (Z = 48) and Zr (Z = 40), Nb (Z = 41), Mo (Z = 42), Tc (Z = 43) isotopes with Z beyond and below Ru (Z = 44), respectively, in Ru the maximal triaxial deformation having been predicted and deduced. The recent measurements and studies of prompt triple- and four-fold, γ-γ-γ and γ-γ-γ-γ, coincidence data from the spontaneous fission of 252Cf using Gammasphere have yielded considerable expansion and extension or first observation of the bands in Ru, Pd, Cd, and Nb isotopes,which provided important data for the studies of nuclear shapes in this region. Combined with previous investigations, recent systematic studies of the new data well reproduced by PES, TRS, PSM, CCCSM and SCTAC model calculations have traced shape changes along the isotonic and isotopic chains, respectively,and with changing excitations/spins as well, significantly expanding our knowledge of shape transitions/coexistence in nuclei.For the neutron-rich Ru and beyond, Rh, Pd, Ag and Cd isotopes, triaxial deformations γ= 28°,slightly smaller than the maximal value, were deduced in Rh (Z = 45) isotopes, with chiral symmetry breaking proposed in 103-106Rh; onset of wobbling motions were identified in 112Ru and 114Pd (N =68),and probably also in 114Ru (N =70); evolution from chiral symmetry breaking in 110,112Ru with maximal triaxial deformations to disturbed chirality in 112,114,116Pd with less pronounced triaxial deformations was proposed; rich nuclear structure was proposed in soft Ag isotopes with possible chiral doubling structure suggested in 104,105Ag, and softness towards triaxial deformation proposed in heavier 115,117Ag;quasi-particle couplings, quasi-rotations and soft triaxiality were suggested in Cd (Z =48) isotopes with small deformations; onset of collectivity was recently suggested in 122,124,126Cd in the vicinity of Z =50 and N = 82 closed shells by studies of Coulomb excitations; shape evolutions from maximal triaxial deformations in Ru (γ=30°, with triaxial minimum energy gain of 0.67 MeV), through Rh with large triaxial deformations ( γ=28°), to less pronounced triaxiality in Pd (with triaxial minimum energy gain of 0.32 MeV), then soft triaxiality in Ag, and finally to slightly deformed Cd isotopes but with emergence of collectivity and soft triaxiality were proposed. The systematic studies of the band crossings in Pd revealed up-rising drivings of the first band crossings caused by (νh11/2)2 and down-sloping drivings of the second band crossings by (πg9/2)2, explained the onset of wobbling motions in 114Pd,and showed a long-sought picture of shape evolution and coexistence in the Pd isotopic chain which is more complete but complex than earlier predictions. Based on the systematic studies in the mass region,maximal triaxial deformation is found to be reached in 112Ru and less-pronounced triaxiality centered at 114Pd, both for N =68, four neutrons more than predicted in earlier theoretical calculations.In the neutron-rich Zr (Z =40), Nb (Z =41), Mo (Z =42) and Tc (Z =43) isotopes with Z just below Ru, large quadrupole deformations of axially symmetric shapes were deduced in Y and Zr isotopes, with emergence of the degree of freedom having been suggested for heavier Zr isotopes; medium triaxial deformations were deduced for the ground states of heavier (A > 104) Nb isotopes, and, with increasing excitations and spins, evolution from medium triaxial deformations with strong quadrupole deformations at ground states to nearly axially-symmetric shapes were deduced; light Nb isotopes (A6103) have near axially-symmetric shapes with strong quadrupole deformations; combining with the identification of onset of strong quadrupole deformation at 100Nb in the Nb isotopic chain, an increase of soft triaxiality with increasing neutron number was proposed in 100-106Nb. Shape coexistence with regard to soft triaxiality is also proposed in Nb isotopes; large triaxial deformations, vibrations and chiral doublets were proposed in Mo isotopes; chiral doubling and large triaxial deformations (γ ~26°) slightly smaller than the maximal triaxiality were suggested in Tc isotopes.The neutron-rich nuclei with Z ranging from 41 through 48 and A ~100 to 126, especially the Pd and Nb isotopes are thus found to be transitional nuclei with regard to triaxiality.
2015, 32(1): 24-29.
doi: 10.11804/NuclPhysRev.32.01.024
Abstract:
The structure effects of project and target in heavy ion collision at low energy is more important compared with the effects at high energy, which requires the transport model to describe the ground properties of nuclei more reasonably. In this paper, we carry out calculations of the ground state properties, such as binding energy and root mean square radius, of different isotope chains from light to heavy mass region by an extended quantum molecular dynamics (EQMD) model and compare the results with data. It is found that the EQMD model not only can reproduce ground state properties of stable nuclei very well, but also can reasonably describe the ground state binding energy of nuclei far from βstability line. Compared with other versions of QMD, EQMD model greatly improves the description of the stability of initialized nuclei. Recent investigations would serve as a starting basis for studying the reaction mechanisms of elastic scattering, fusion, transfer and breakup induced by weakly bound nuclei by the microscopic dynamical model.
The structure effects of project and target in heavy ion collision at low energy is more important compared with the effects at high energy, which requires the transport model to describe the ground properties of nuclei more reasonably. In this paper, we carry out calculations of the ground state properties, such as binding energy and root mean square radius, of different isotope chains from light to heavy mass region by an extended quantum molecular dynamics (EQMD) model and compare the results with data. It is found that the EQMD model not only can reproduce ground state properties of stable nuclei very well, but also can reasonably describe the ground state binding energy of nuclei far from βstability line. Compared with other versions of QMD, EQMD model greatly improves the description of the stability of initialized nuclei. Recent investigations would serve as a starting basis for studying the reaction mechanisms of elastic scattering, fusion, transfer and breakup induced by weakly bound nuclei by the microscopic dynamical model.
2015, 32(1): 30-35.
doi: 10.11804/NuclPhysRev.32.01.030
Abstract:
We studied the evolution of the collective motion, interaction potential, the total kinetic and excitation energies in ternary ssions of 197Au +197Au system at 15 Mev/u, and discussed energy dissipation of this reaction. Through the comparison with energy-angle correlation data in binary ssions, we preliminarily concluded that the rst ssion of ternary ssion was an extreme deep-inelastic process. We further analyzed the correlation of the total kinetic energy with impact parameters in both binary and ternary reactions, and found that the total energy of binary reactions systems was lost about 150 MeV more than ternary ssion with small impact parameters, and with larger impact parameters the total energy of ternary reactions were lost 300 MeV more than binary reactions.
We studied the evolution of the collective motion, interaction potential, the total kinetic and excitation energies in ternary ssions of 197Au +197Au system at 15 Mev/u, and discussed energy dissipation of this reaction. Through the comparison with energy-angle correlation data in binary ssions, we preliminarily concluded that the rst ssion of ternary ssion was an extreme deep-inelastic process. We further analyzed the correlation of the total kinetic energy with impact parameters in both binary and ternary reactions, and found that the total energy of binary reactions systems was lost about 150 MeV more than ternary ssion with small impact parameters, and with larger impact parameters the total energy of ternary reactions were lost 300 MeV more than binary reactions.
2015, 32(1): 36-43.
doi: 10.11804/NuclPhysRev.32.01.036
Abstract:
The relations between wave packet width and projectile fragmentation cross sections are studied in theory by using the improved quantum molecular dynamics (ImQMD) and GEMINI models. The effect of different wave packet width for projectile fragmentation cross sections is analyzed for the reaction 36Ar on C, 20Ne on C, Al, Cu, Sn at 400 AMeV, the isotope distributions with different wave packet width are studied for reactions 36Ar, 40Ar on Al. The results show that the projectile fragmentation cross sections are affected by the choice of the wave packet width, and are related to the system of nuclear reaction. The calculation results of σ2r =2 fm2are in agreement with the experimental results, but the results of σr = (0.88+0.09A1/3) fm have a strong relation with reaction system and the projectile fragmentation cross sections are affected obviously. The influence of wave packet width for 40Ar projectile fragmentation cross sections is smaller than that for 36Ar.Moreover isotope distributions with system-size-dependent wave packet width are larger than with σ2r =2 fm2.
The relations between wave packet width and projectile fragmentation cross sections are studied in theory by using the improved quantum molecular dynamics (ImQMD) and GEMINI models. The effect of different wave packet width for projectile fragmentation cross sections is analyzed for the reaction 36Ar on C, 20Ne on C, Al, Cu, Sn at 400 AMeV, the isotope distributions with different wave packet width are studied for reactions 36Ar, 40Ar on Al. The results show that the projectile fragmentation cross sections are affected by the choice of the wave packet width, and are related to the system of nuclear reaction. The calculation results of σ2r =2 fm2are in agreement with the experimental results, but the results of σr = (0.88+0.09A1/3) fm have a strong relation with reaction system and the projectile fragmentation cross sections are affected obviously. The influence of wave packet width for 40Ar projectile fragmentation cross sections is smaller than that for 36Ar.Moreover isotope distributions with system-size-dependent wave packet width are larger than with σ2r =2 fm2.
2015, 32(1): 44-49.
doi: 10.11804/NuclPhysRev.32.01.044
Abstract:
Recently, Diakonov considered the sea quark effect of baryon resonance spectrum in the large Nc mean field approximation and put forward the collective excitation theory of baryon resonance spectrum, which is an extension of the SU(6) quark model. In this paper we examine the implications of the meson tensor potential of the Diakonov’s baryon spectrum theory and provide a numerical optimization of the parameters in the baryon resonance spectrum formula. The resulted baryon resonance spectrum formula is in good agreement with the spectra data below 2 GeV.
Recently, Diakonov considered the sea quark effect of baryon resonance spectrum in the large Nc mean field approximation and put forward the collective excitation theory of baryon resonance spectrum, which is an extension of the SU(6) quark model. In this paper we examine the implications of the meson tensor potential of the Diakonov’s baryon spectrum theory and provide a numerical optimization of the parameters in the baryon resonance spectrum formula. The resulted baryon resonance spectrum formula is in good agreement with the spectra data below 2 GeV.
2015, 32(1): 50-53.
doi: 10.11804/NuclPhysRev.32.01.050
Abstract:
The RFQ beam dynamics of a heavy ion linac was investigated in this paper and the BEAMPATH code was employed in this study. The main research was focused on the beam performances depending on longitudinal acceptance, RF properties, beam instability and space charge effect. The RFQ has large longitudinal acceptance in design, which brings the beam performances well. In the RF parameter study, the beam can keep good transmission in the acceleration even the vane voltage is larger than the theoretical value. It is also shown that the RFQ has a large robustness for the mismatch of the input beam by the analysis of the beam instability.Furthermore, the beam evolution is independent on the space charge effect when the beam current is less than 0.5 emA. The preliminary analysis of the beam dynamics shows that the 53.667 MHz heavy ion RFQ has a promising performance, which meets the requirements of SSC-LINAC.
The RFQ beam dynamics of a heavy ion linac was investigated in this paper and the BEAMPATH code was employed in this study. The main research was focused on the beam performances depending on longitudinal acceptance, RF properties, beam instability and space charge effect. The RFQ has large longitudinal acceptance in design, which brings the beam performances well. In the RF parameter study, the beam can keep good transmission in the acceleration even the vane voltage is larger than the theoretical value. It is also shown that the RFQ has a large robustness for the mismatch of the input beam by the analysis of the beam instability.Furthermore, the beam evolution is independent on the space charge effect when the beam current is less than 0.5 emA. The preliminary analysis of the beam dynamics shows that the 53.667 MHz heavy ion RFQ has a promising performance, which meets the requirements of SSC-LINAC.
2015, 32(1): 54-58.
doi: 10.11804/NuclPhysRev.32.01.054
Abstract:
The EM design of a 325 MHz β= 0.52 superconducting double Spoke cavity has been finished at Institute of Modern Physics (IMP), Chinese Academy of Sciences(CAS). In this paper, the optimization of the Spoke base is described in detail. The goal is to minimize the peak surface field and maximize the shunt impedance. The common cylinder is replaced by the racetrack shape for the Spoke base. The transverse racetrack Spoke base can offer a better RF property than the longitudinal racetrack Spoke base, which meet the requirement of the C-ADS. The simulation of multipactor finished by CST Particle Studio is also presented, which gives a promising result that there is no multipactor around working voltage.
The EM design of a 325 MHz β= 0.52 superconducting double Spoke cavity has been finished at Institute of Modern Physics (IMP), Chinese Academy of Sciences(CAS). In this paper, the optimization of the Spoke base is described in detail. The goal is to minimize the peak surface field and maximize the shunt impedance. The common cylinder is replaced by the racetrack shape for the Spoke base. The transverse racetrack Spoke base can offer a better RF property than the longitudinal racetrack Spoke base, which meet the requirement of the C-ADS. The simulation of multipactor finished by CST Particle Studio is also presented, which gives a promising result that there is no multipactor around working voltage.
2015, 32(1): 59-62.
doi: 10.11804/NuclPhysRev.32.01.059
Abstract:
A double-pulse laser irradiating scheme has been designed and established for the production of highly charged ion beams at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The laser beam output by a Nd:YAG laser is split and combined by a double of beam splitters, between which the split laser beams are transmitted along different optical paths to get certain time delay between each other. With the help of a quarter-wave plate before the first splitter, the energy ratio between the two laser pulses can be adjusted between 3:8 to 8:3. To testify its feasibility, a preliminary experiment was carried out with the new-developed double-pulse irradiating scheme to produce highly charged carbon ions. Comparing the results with those got from the previous single-pulse irradiating scheme, the differences in the time structure and Charge State Distribution (CSD) of the ion pulse were observed, but its mechanisms and optimization require further studies.
A double-pulse laser irradiating scheme has been designed and established for the production of highly charged ion beams at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The laser beam output by a Nd:YAG laser is split and combined by a double of beam splitters, between which the split laser beams are transmitted along different optical paths to get certain time delay between each other. With the help of a quarter-wave plate before the first splitter, the energy ratio between the two laser pulses can be adjusted between 3:8 to 8:3. To testify its feasibility, a preliminary experiment was carried out with the new-developed double-pulse irradiating scheme to produce highly charged carbon ions. Comparing the results with those got from the previous single-pulse irradiating scheme, the differences in the time structure and Charge State Distribution (CSD) of the ion pulse were observed, but its mechanisms and optimization require further studies.
2015, 32(1): 63-68.
doi: 10.11804/NuclPhysRev.32.01.063
Abstract:
The existed Kicker Control System for HIRFL-CSR in Lanzhou is multi-board and many software interfaces have been installed to have the parameters to be con gurated. The time resolution for the beam to be identi ed is 5 ns. The newly designed Kicker Control System is designed with single-board architecture and raises the system time resolution to 2.5 ns. The B/S model has been applied to upgrade the software interface.In order to realize the target, we use the browser to communicate with hardware for the purpose of con guring the controller, the Boa web server has been transplanted into embedded system. The experiments showed that this software system is easy to use and integrate with other control system, without setup process, and is of great research value and popularization.
The existed Kicker Control System for HIRFL-CSR in Lanzhou is multi-board and many software interfaces have been installed to have the parameters to be con gurated. The time resolution for the beam to be identi ed is 5 ns. The newly designed Kicker Control System is designed with single-board architecture and raises the system time resolution to 2.5 ns. The B/S model has been applied to upgrade the software interface.In order to realize the target, we use the browser to communicate with hardware for the purpose of con guring the controller, the Boa web server has been transplanted into embedded system. The experiments showed that this software system is easy to use and integrate with other control system, without setup process, and is of great research value and popularization.
2015, 32(1): 69-72.
doi: 10.11804/NuclPhysRev.32.01.069
Abstract:
ZnO ultraviolet(UV) detectors with Metal-Semiconductor-Metal(MSM) structure were fabricated by the vacuum evaporation of Au, Ag, and Al on the n-type ZnO single crystal, which was grown with hydrothermal synthesis method. Five types of MSM ZnO detectors(Au-ZnO-Au, Ag-ZnO-Ag, Au-ZnO-Al, Ag-ZnO-Al,l-ZnO-Al) were illuminated with 365 nm UV light respectively, and their corresponding I-V(Current-Voltage) characteristics were measured. The UV photocurrent values for Au-ZnO-Au and Ag-ZnO-Ag detectors were 1x106 times than their dark current values, and these facts imply that the Au-ZnO-Au and Ag-ZnO-Ag detectors were rather good UV detectors compared to Au-ZnO-Al, Ag-ZnO-Al, Al-ZnO-Al detectors. The photocurrent of the MSM ZnO detectors was also sensitive to the cubic resistance of the ZnO crystal. And it’s found that the higher resistance rate the ZnO crystal the smaller photocurrent value the detector under the same working voltage.
ZnO ultraviolet(UV) detectors with Metal-Semiconductor-Metal(MSM) structure were fabricated by the vacuum evaporation of Au, Ag, and Al on the n-type ZnO single crystal, which was grown with hydrothermal synthesis method. Five types of MSM ZnO detectors(Au-ZnO-Au, Ag-ZnO-Ag, Au-ZnO-Al, Ag-ZnO-Al,l-ZnO-Al) were illuminated with 365 nm UV light respectively, and their corresponding I-V(Current-Voltage) characteristics were measured. The UV photocurrent values for Au-ZnO-Au and Ag-ZnO-Ag detectors were 1x106 times than their dark current values, and these facts imply that the Au-ZnO-Au and Ag-ZnO-Ag detectors were rather good UV detectors compared to Au-ZnO-Al, Ag-ZnO-Al, Al-ZnO-Al detectors. The photocurrent of the MSM ZnO detectors was also sensitive to the cubic resistance of the ZnO crystal. And it’s found that the higher resistance rate the ZnO crystal the smaller photocurrent value the detector under the same working voltage.
2015, 32(1): 73-79.
doi: 10.11804/NuclPhysRev.32.01.073
Abstract:
This article introduces a high resolution and multi-channel scaler based on PXI-3U standard. The maximum repetition frequency of the input signal is 100 MHz, with a counting scale up to 240. This scaler is able to operate in two working modes: counting within a certain time period or between two adjacent input trigger signals. The rst mode is designed for a low counting rate (~ 1 MHz), while the second mode for a high rate ( 100 MHz). Test results indicate that this scaler has a good performance, beyond the application requirement in the experiment of the reaction microscope at Lanzhou (ReMiLa). Besides, with the application of Field Programmable Gate Array (FPGA), this scaler module is exible and convenient to be upgrade in future.
This article introduces a high resolution and multi-channel scaler based on PXI-3U standard. The maximum repetition frequency of the input signal is 100 MHz, with a counting scale up to 240. This scaler is able to operate in two working modes: counting within a certain time period or between two adjacent input trigger signals. The rst mode is designed for a low counting rate (~ 1 MHz), while the second mode for a high rate ( 100 MHz). Test results indicate that this scaler has a good performance, beyond the application requirement in the experiment of the reaction microscope at Lanzhou (ReMiLa). Besides, with the application of Field Programmable Gate Array (FPGA), this scaler module is exible and convenient to be upgrade in future.
2015, 32(1): 80-83.
doi: 10.11804/NuclPhysRev.32.01.080
Abstract:
For estimating the influence of the projectile breakup reaction on carbon ion tumour therapy, a detector system was built by IMP(Institute of Modern Physics), Chinese Academy of Sciences(CAS), and used to detect the results of the reaction. The system is composed of start detector, water target system, charged fragments detector system and neutron detector system. The performance of the detector system was tested in the experiment of 5 cm thick water target bombarded by 250 MeV/u carbon beam. The results reveal that the charged fragments, such as elements H, He, Li, Be, B and C, were identified clearly by ΔE-E and ΔE-TOF techniques. The angular distributions of some charged fragments were obtained by calculating the charge-changing cross-sections of the fragments(e.g. elements H and He isotopes in our work). The test results prove that the charged fragment detector system achieves the design aim.
For estimating the influence of the projectile breakup reaction on carbon ion tumour therapy, a detector system was built by IMP(Institute of Modern Physics), Chinese Academy of Sciences(CAS), and used to detect the results of the reaction. The system is composed of start detector, water target system, charged fragments detector system and neutron detector system. The performance of the detector system was tested in the experiment of 5 cm thick water target bombarded by 250 MeV/u carbon beam. The results reveal that the charged fragments, such as elements H, He, Li, Be, B and C, were identified clearly by ΔE-E and ΔE-TOF techniques. The angular distributions of some charged fragments were obtained by calculating the charge-changing cross-sections of the fragments(e.g. elements H and He isotopes in our work). The test results prove that the charged fragment detector system achieves the design aim.
2015, 32(1): 84-88.
doi: 10.11804/NuclPhysRev.32.01.084
Abstract:
In order to obtain detection efficiencies of nine kinds of gamma rays emitted by isotopes deposited in lungs at various measurement geometry, Monte Carlo N-Particle Transport Code 5 (MCNP5) has been employed to for calculation. The results show that the detection efficiency in different locations of lung is not completely accord with human body’s anatomy structure. The efficiency decreases gradually from lower-right lung, to lowerleft lung, and then to upper-left lung. When the location of detector is fixed, with the increase of energy, the
detection efficiency rises up firstly and then falls down.
In order to obtain detection efficiencies of nine kinds of gamma rays emitted by isotopes deposited in lungs at various measurement geometry, Monte Carlo N-Particle Transport Code 5 (MCNP5) has been employed to for calculation. The results show that the detection efficiency in different locations of lung is not completely accord with human body’s anatomy structure. The efficiency decreases gradually from lower-right lung, to lowerleft lung, and then to upper-left lung. When the location of detector is fixed, with the increase of energy, the
detection efficiency rises up firstly and then falls down.
Structures in Fully Differential Cross Sections for the Single Ionization of He by 2 MeV/amu C6+ Ion
2015, 32(1): 89-94.
doi: 10.11804/NuclPhysRev.32.01.089
Abstract:
The modified coulomb born (MCB) model is applied to study the single ionization of helium by 2 MeV/amu C6+ ion. The fully differential cross sections are presented for a variety of momentum transfers and ejected-electron energies in the scattering plane. The MCB results are compared with the experimental data and other theoretical predictions. We find that the MCB results are similar to the 3CW (three-body coulomb wave) results and they are superior to the 3DW-EIS (three-body distorted wave-eikonal initial state) results. It turns out that the treatment of the passive electron is very important for the results and distorting effects are not obvious.
The modified coulomb born (MCB) model is applied to study the single ionization of helium by 2 MeV/amu C6+ ion. The fully differential cross sections are presented for a variety of momentum transfers and ejected-electron energies in the scattering plane. The MCB results are compared with the experimental data and other theoretical predictions. We find that the MCB results are similar to the 3CW (three-body coulomb wave) results and they are superior to the 3DW-EIS (three-body distorted wave-eikonal initial state) results. It turns out that the treatment of the passive electron is very important for the results and distorting effects are not obvious.
2015, 32(1): 95-99.
doi: 10.11804/NuclPhysRev.32.01.095
Abstract:
The present work investigates the irradiation hardening of ODS ferritic steels after multi-energy Heion implantation, or energetic Bi-ion and Xe-ion irradiation, to get an understanding of dependence of irradiationhardening on atomic displacement damage and gas accumulation. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-0.1Zr ODS ferritic steels were used.The results show that the hardness increases rapidly at the lower doses but tends to saturate at the higher dose.An 1/2-power law dependence on dpa value is obtained. Helium implantation contributes significantly to the irradiation hardening, possibly due to the impediment of the motion dislocations by helium bubbles. 16Cr-ODS (Ti or Zr added) ferritic which contains finer oxide particles in higher number density shows higher resistance to irradiation hardening than the MA056.
The present work investigates the irradiation hardening of ODS ferritic steels after multi-energy Heion implantation, or energetic Bi-ion and Xe-ion irradiation, to get an understanding of dependence of irradiationhardening on atomic displacement damage and gas accumulation. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-0.1Zr ODS ferritic steels were used.The results show that the hardness increases rapidly at the lower doses but tends to saturate at the higher dose.An 1/2-power law dependence on dpa value is obtained. Helium implantation contributes significantly to the irradiation hardening, possibly due to the impediment of the motion dislocations by helium bubbles. 16Cr-ODS (Ti or Zr added) ferritic which contains finer oxide particles in higher number density shows higher resistance to irradiation hardening than the MA056.
2015, 32(1): 100-104.
doi: 10.11804/NuclPhysRev.32.01.100
Abstract:
This work investigates the effect of nuclear reactions resulting from the interaction of heavyion with the specific devices on single event upset (SEU), since the traditional application of linear energy transfer (LET) as an engineering metric may be unsatisfied on SEU characterization or has no ability to directly present the property of nuclear reaction (including its probability and secondary ions). Using Monte Carlo simulation and in-depth analysis, this study provides a powerful comparison between direct ionization processes and the one within nuclear reactions. The different heavy ions have been applied in simulation to characterize the role of nuclear reactions in SEU occurrence. The results show that the contribution of heavy-ion nuclear reactions to SEU cross section depends on ion energy with a nonmonotonic relationship. Based on the simulated results, suggestions were put forward that the worst case of SEU occurrence induced by heavy-ion nuclear reactions should be considered to predict the on-orbit SEU rate.
This work investigates the effect of nuclear reactions resulting from the interaction of heavyion with the specific devices on single event upset (SEU), since the traditional application of linear energy transfer (LET) as an engineering metric may be unsatisfied on SEU characterization or has no ability to directly present the property of nuclear reaction (including its probability and secondary ions). Using Monte Carlo simulation and in-depth analysis, this study provides a powerful comparison between direct ionization processes and the one within nuclear reactions. The different heavy ions have been applied in simulation to characterize the role of nuclear reactions in SEU occurrence. The results show that the contribution of heavy-ion nuclear reactions to SEU cross section depends on ion energy with a nonmonotonic relationship. Based on the simulated results, suggestions were put forward that the worst case of SEU occurrence induced by heavy-ion nuclear reactions should be considered to predict the on-orbit SEU rate.
2015, 32(1): 105-109.
doi: 10.11804/NuclPhysRev.32.01.105
Abstract:
Heavy ion irradiation is a perfect means in radio-therapy due to its special depth dose distribution and high relative biological effects. The biological effects of heavy ion irradiation are determined by some major physical parameters, and vary along the tracks of heavy ions. Therefore, it is very significant for the tumor radio-therapy to investigate the biological effects along whole range of heavy ion radiation. In the present study, Caenorhabditis elegans, a model in vivo, was irradiated by carbon ion beams from HCRFL-CSRe, The level of germ cell apoptosis of worms was used as a checking endpoint for DNA damage, the effects of carbon irradiation located in the entrance, plateau and peak regions on the genomic instability of the irradiated worm and their progeny were detected. The results showed that the 10 and 20 Gy of carbon ion radiations led to the increased germ cell apoptosis in irradiated worms and these effects depend on the worm location along the range of carbon ions and the irradiation dosage. The results also suggested that heavy ion irradiation induced the up-regulated genomic instability in their progeny, and might be related to both the irradiation dose and the irradiated location.
Heavy ion irradiation is a perfect means in radio-therapy due to its special depth dose distribution and high relative biological effects. The biological effects of heavy ion irradiation are determined by some major physical parameters, and vary along the tracks of heavy ions. Therefore, it is very significant for the tumor radio-therapy to investigate the biological effects along whole range of heavy ion radiation. In the present study, Caenorhabditis elegans, a model in vivo, was irradiated by carbon ion beams from HCRFL-CSRe, The level of germ cell apoptosis of worms was used as a checking endpoint for DNA damage, the effects of carbon irradiation located in the entrance, plateau and peak regions on the genomic instability of the irradiated worm and their progeny were detected. The results showed that the 10 and 20 Gy of carbon ion radiations led to the increased germ cell apoptosis in irradiated worms and these effects depend on the worm location along the range of carbon ions and the irradiation dosage. The results also suggested that heavy ion irradiation induced the up-regulated genomic instability in their progeny, and might be related to both the irradiation dose and the irradiated location.
2015, 32(1): 110-114.
doi: 10.11804/NuclPhysRev.32.01.110
Abstract:
Human gastric cancer cell SGC7901 were irradiated with high linear energy transfer (LET) carbon ion. Apoptotic cells after irradiation were analyzed by flow cytometry and expression of MSH2 genes in the irradiated cells was detected by western blot and RT-PCR assay. Compared with the control group, we found that the number of G2/M (33.26±0.08) or apoptosis (24.16±0.64) of SGC7901 cells reached a maximum after irradiation at 72 h in a dose dependent manner. And heavy ion irradiation efficiently up-regulated the expression of MSH2 gene at 4.0 Gy after being irradiated 6 h. These results imply that heavy ion beam could induce cell apoptosis and cell cycle arrest in time-dependent manners. Furthermore, expression of MSH2 genes activated by carbon ion irradiation suggests that DNA mismatch repair gene MSH2 might be involved in DNA repair pathways.
Human gastric cancer cell SGC7901 were irradiated with high linear energy transfer (LET) carbon ion. Apoptotic cells after irradiation were analyzed by flow cytometry and expression of MSH2 genes in the irradiated cells was detected by western blot and RT-PCR assay. Compared with the control group, we found that the number of G2/M (33.26±0.08) or apoptosis (24.16±0.64) of SGC7901 cells reached a maximum after irradiation at 72 h in a dose dependent manner. And heavy ion irradiation efficiently up-regulated the expression of MSH2 gene at 4.0 Gy after being irradiated 6 h. These results imply that heavy ion beam could induce cell apoptosis and cell cycle arrest in time-dependent manners. Furthermore, expression of MSH2 genes activated by carbon ion irradiation suggests that DNA mismatch repair gene MSH2 might be involved in DNA repair pathways.
2015, 32(1): 115-120.
doi: 10.11804/NuclPhysRev.32.01.115
Abstract:
To characterize the theoretical basis of eld patching technique in carbon ion beam therapy, Monte Carlo software package Gate/Geant4 was used to simulate the lateral dose distribution of matched elds. The lateral dose distribution of the matched elds within 1.0 millimeter of patient positioning error and the relationship between the central dose of the matched elds and the eld patching gap were obtained. Moreover, the lateral dose pro le of eld patching irradiation with 5.0 mm gap was simulated. While comparing the lateral dose distribution of eld patching irradiation with 5.0 mm gap with the undivided eld irradiation, a good agreement between both results with a maximum dose deviation of 6.8% was observed within the target volume.Hence a feasible method for solving the issue of dose hotspots during eld patching under the condition of higher patient positioning accuracies (patient positioning error within 1.0 millimeter) was proposed and the dose homogeneit within the target volume could be greatly improved when eld patching technique is adopted in carbon ion beam therapy.
To characterize the theoretical basis of eld patching technique in carbon ion beam therapy, Monte Carlo software package Gate/Geant4 was used to simulate the lateral dose distribution of matched elds. The lateral dose distribution of the matched elds within 1.0 millimeter of patient positioning error and the relationship between the central dose of the matched elds and the eld patching gap were obtained. Moreover, the lateral dose pro le of eld patching irradiation with 5.0 mm gap was simulated. While comparing the lateral dose distribution of eld patching irradiation with 5.0 mm gap with the undivided eld irradiation, a good agreement between both results with a maximum dose deviation of 6.8% was observed within the target volume.Hence a feasible method for solving the issue of dose hotspots during eld patching under the condition of higher patient positioning accuracies (patient positioning error within 1.0 millimeter) was proposed and the dose homogeneit within the target volume could be greatly improved when eld patching technique is adopted in carbon ion beam therapy.
2015, 32(1): 121-127.
doi: 10.11804/NuclPhysRev.32.01.121
Abstract:
To meet the needs for nuclear data engineering, the experimental data of the 65Cu(n, p)65Ni cross section below 20 MeV were analyzed and evaluated.The evaluation procedure includes the experimental data collection, correction, selection, normalization, error adjustment and data processing, especially the covariance matrix for each experimental data is constructed with the information on experimental errors and correlation errors. The evaluation cross section data and the corresponding covariance matrices were given using the spline fitting procedure SPCC. The evaluation work was done with the consideration of not only the experimental errors but also the correlation of data.
To meet the needs for nuclear data engineering, the experimental data of the 65Cu(n, p)65Ni cross section below 20 MeV were analyzed and evaluated.The evaluation procedure includes the experimental data collection, correction, selection, normalization, error adjustment and data processing, especially the covariance matrix for each experimental data is constructed with the information on experimental errors and correlation errors. The evaluation cross section data and the corresponding covariance matrices were given using the spline fitting procedure SPCC. The evaluation work was done with the consideration of not only the experimental errors but also the correlation of data.
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